Apparatuses of this type have already been described in international applications WO 91/07662 and WO 96/14582 to which reference may be made for a description of the assays performed, those known apparatuses essentially comprising means for supporting, guiding, and displacing reaction wells stepwise along a path comprising a predetermined number of positions, a turntable for supporting samples to be analyzed, a turntable for supporting reagents, means for taking determined quantities of samples and of reagents and for injecting these quantities into the reaction wells, means for washing the wells, means for optically reading assay results, and a controlling computer system enabling previously-programmed analysis cycles to be performed corresponding to assays of the single-reagent type or of the two-reagent type, the first of said known apparatuses operating at a rate of about 120 assays per hour, while the second operates at about 360 assays per hour.
The apparatus described in international application WO 96/14582 is further distinguished in that it is designed to operate with reaction modules constituted by molded plastics parts each comprising an aligned plurality of reaction wells that are integrally secured with one another, said reaction modules being mass-produced at very low cost, thereby enabling them to be disposed of after being used once only. In addition, those reaction modules are stackable, thus making them easier to package and also facilitating stacking of the modules in automated feed means of the apparatus.
That known apparatus is also characterized by means for guiding and displacing reaction modules along an open loop track that is U-shaped, with means for automatically feeding reaction modules being provided at one end, and means for automatically ejecting reaction modules being provided at the other.
That apparatus has the advantage of operating at a high rate (360 assays per hour), but it is bulkier and more expensive than the apparatus described in international application WO 91/07662.